The present invention relates generally nozzles for directional control of aircraft, and more particularly to a uniquely configured nozzle requiring reduced mass flow for yaw control augmentation of an aircraft.
The maneuver envelope and agility of fighter aircraft are limited in part by undesirably limited yaw control as angle of attack increases. As angle of attack increases, power required to coordinate a velocity vector roll maneuver increases to levels higher than that which conventional rudders can provide. Consequently, up to 75% of maximum achievable roll rate may be lost in the maneuver envelope. Vertical tail structural fatigue is a significant problem in fighter aircraft maintenance and augmentation of aircraft yaw power with forebody thrust nozzles for directional control may allow downsizing vertical tail surfaces.
Conventional forebody nozzle structures are generally limited to simple circular exit geometry shape and to pointing directions tangentially aft or forward, and therefore have effectiveness too limited for practical aircraft installations. The required mass flows are too high, and the trending with angles of attack and sideslip is not well behaved. The applicable range of effectiveness is limited to post stall angles of attack.
The invention solves or substantially reduces in critical importance problems in prior art structures as just suggested by providing a forebody thrust nozzle structure for augmenting yaw control of an aircraft wherein a unique combination of nozzle structure and orientation provide increased aircraft directional control. The nozzles are preferably located about 0.5 forebody diameter aft of the nose apex, and about 45.degree. on either side of the plane of symmetry on the top side of the forebody. The nozzles are sized according to the available air pressure and are directed toward the plane of symmetry at about 60.degree.. The added directional control provided by the forebody nozzles increases agility and maneuverability of fighter aircraft in both the conventional combat envelope and the post stall envelope.
It is therefore a principal object of the invention to provide an improved forebody nozzle configuration for directional control of an aircraft.
It is a further object of the invention to provide a forebody nozzle for augmenting yaw control of an aircraft.
These and other objects of the invention will become apparent as a detailed description of representative embodiments proceeds.